Amine-linked diglycosides: Synthesis facilitated by the enhanced reactivity of allylic electrophiles, and glycosidase inhibition assays

• Ian Cumpstey,
• Jens Frigell,
• Elias Pershagen,
• Tashfeen Akhtar,
• Elena Moreno-Clavijo,
• Inmaculada Robina,
• Dominic S. Alonzi and
• Terry D. Butters

Beilstein J. Org. Chem. 2011, 7, 1115–1123, doi:10.3762/bjoc.7.128

• synthesis of carbasugar pseudodisaccharides [36]. Treatment of the imidate 23 with an amine nucleophile 5 [33] and a palladium catalyst [21] resulted in the formation of four products, 24 (44%), 25 (15%), 26 (5%) and 27 (6%), which were assigned the structures given in Scheme 5. Three of 24–26 were isomeric

Au(I)/Au(III)-catalyzed Sonogashira-type reactions of functionalized terminal alkynes with arylboronic acids under mild conditions

• Deyun Qian and
• Junliang Zhang

Beilstein J. Org. Chem. 2011, 7, 808–812, doi:10.3762/bjoc.7.92

• , pharmaceuticals and other materials [1][2][3]. In the past decade, considerable efforts have been made to enhance the efficiency and generality of this reaction. All kinds of palladium catalyst systems [4][5][6][7][8][9][10] and other metal catalyst systems [3] have been developed for facilitating the Sonogashira

Synthesis, reactivity and biological activity of 5-alkoxymethyluracil analogues

• Lucie Brulikova and
• Jan Hlavac

Beilstein J. Org. Chem. 2011, 7, 678–698, doi:10.3762/bjoc.7.80

• -chloromercuri-2'-deoxyuridine, and a palladium catalyst. The reaction, carried out in methanol, afforded 17% of (E)-5-(3,3,3-trifluoro-1-propenyl)-2'-deoxyuridine (6) and 36% of 5-(3,3,3-trifluoro-1-methoxypropyl)-2'-deoxyuridine (1) (Scheme 1). Shortly after publishing the successful synthesis of trifluoro

• organopalladium analogue via the reaction with 0.1 M palladium catalyst and ethene in methanol. Surprisingly, the major product of the reaction was the methoxy derivative 96 in 39% yield instead of the expected 5-vinyluridine (24). Similarly, the 2'-deoxyuridine organomercuri derivative 4 reacted with propene in

• presence of a palladium catalyst (Scheme 26). The vinyl derivatives 157 and 158 were obtained as major products. However, methoxy derivatives 151 and 152 were produced in modest yields. The monophosphate derivatives 153 and 154 were formed by a similar reaction with mercuriated 2'-deoxyuridine

Synthesis of cross-conjugated trienes by rhodium-catalyzed dimerization of monosubstituted allenes

• Tomoya Miura,
• Tsuneaki Biyajima,
• Takeharu Toyoshima and
• Masahiro Murakami

Beilstein J. Org. Chem. 2011, 7, 578–581, doi:10.3762/bjoc.7.67

• stereoselective manner to give cross-conjugated trienes, which are different from those obtained by a palladium catalyst. Keywords: allene; cross-conjugated triene; dimerization; rhodium; stereoselective; Introduction Cross-conjugated trienes, known as [3]dendralenes [1], are attractive synthetic precursors

• substituted cross-conjugated trienes 2 in high yield (Scheme 1) [21]. We report here that dimerization of monosubstituted allenes is also catalyzed by a rhodium(I)/dppe complex to form cross-conjugated trienes 3, which are different from those obtained with the palladium catalyst. Results and Discussion We

• complex, allowing the stereoselective formation of substituted cross-conjugated trienes. It is interesting that the rhodium catalyst and the palladium catalyst gave different types of cross-conjugated trienes. Experimental General procedure for rhodium-catalyzed dimerization of monosubstituted allenes To

Air-stable, recyclable, and time-efficient diphenylphosphinite cellulose-supported palladium nanoparticles as a catalyst for Suzuki–Miyaura reactions

• Qingwei Du and
• Yiqun Li

Beilstein J. Org. Chem. 2011, 7, 378–385, doi:10.3762/bjoc.7.48

• the Cell–OPPh2–Pd0, indicating coordination of the phosphine atom with the palladium and further confirming the formation of a palladium complex on the surface of the polymer. Figure 1 shows the XRD pattern of the cellulose-supported palladium catalyst and the Cell–OPPh2 matrix. The Cell–OPPh2

• , 756, 728 cm−1. XRD pattern of the cellulose-supported palladium catalyst and Cell–OPPh2 matrix. TG curve of the cellulose and Cell–OPPh2–Pd0 under nitrogen flow. SEM images of the Cell–OPPh2 (a) and the fresh catalyst Cell–OPPh2–Pd0 (b). TEM image of the fresh Cell–OPPh2–Pd0 catalyst (a) and the

C–C (alkynylation) vs C–O (ether) bond formation under Pd/C–Cu catalysis: synthesis and pharmacological evaluation of 4-alkynylthieno[2,3-d]pyrimidines

• Dhilli Rao Gorja,
• K. Shiva Kumar,
• K. Mukkanti and
• Manojit Pal

Beilstein J. Org. Chem. 2011, 7, 338–345, doi:10.3762/bjoc.7.44

• -tetrahydrobenzothieno[2,3-d]pyrimidine. The use of another palladium catalyst (PPh3)2PdCl2 was also examined and found to be effective (Table 1, entry 7). However, we preferred to use Pd/C because it is less expensive, easy to handle and separable from the product and has the potential for recyclability, for a review

Studies on Pd/NiFe₂O₄ catalyzed ligand-free Suzuki reaction in aqueous phase: synthesis of biaryls, terphenyls and polyaryls

• Sanjay R. Borhade and
• Suresh B. Waghmode

Beilstein J. Org. Chem. 2011, 7, 310–319, doi:10.3762/bjoc.7.41

• authors have reported good yields of terphenyls and polyaryls, the fact that the precious palladium catalyst is non-recoverable renders these processes commercially undesirable. The first use of heterogeneous Pd-modified silica catalyst for consecutive Suzuki reactions was reported by Clark et al. for the

Palladium-catalyzed formation of oxazolidinones from biscarbamates: a mechanistic study

• Benan Kilbas and
• Metin Balci

Beilstein J. Org. Chem. 2011, 7, 246–253, doi:10.3762/bjoc.7.33

• of the palladium catalyst in THF, prepared from tris(dibenzylideneacetone)dipalladium chloroform complex and triisopropyl phosphite. The resulting oxazolidinone 9 was purified by chromatography on a silica gel column to give a crystalline product in 58% yield. The structure and configuration of 9 was

• diacetates 15 and 18b. The isomeric diols 14 and 18a were treated with 2 equiv of toluenesulfonyl isocyanate as described above to give the corresponding biscarbamates 16 and 19. Treatment of 16 and 19 with the palladium catalyst (as described above) resulted in the formation of oxazolidinone derivatives 17

Pd-catalyzed decarboxylative Heck vinylation of 2-nitrobenzoates in the presence of CuF₂

• Lukas J. Gooßen,
• Bettina Zimmermann and
• Thomas Knauber

Beilstein J. Org. Chem. 2010, 6, No. 43, doi:10.3762/bjoc.6.43

• formation of the desired product, albeit in the expected low yields. After some optimization, we were able to convert the electron-poor 2-nitrostilbene (3aa) in high yields even when lowering the palladium catalyst loading from 20 mol % to 5 mol %, and the amount of silver carbonate from 3 to 1.5

• decarboxylated at a palladium catalyst. The coupling of electron-poor 2-nitrobenzoates was achieved by combining a copper-mediated decarboxylation with a palladium-catalyzed Heck coupling. The new mechanistic pathway is likely to open up new perspectives for decarboxylative Heck reactions by overcoming some

Diastereoselective functionalisation of benzo-annulated bicyclic sultams: Application for the synthesis of cis-2,4-diarylpyrrolidines

• Susan Kelleher,
• Pierre-Yves Quesne and
• Paul Evans

Beilstein J. Org. Chem. 2009, 5, No. 69, doi:10.3762/bjoc.5.69

• ). Therefore, a one-pot method was developed based on recent reports which demonstrate that the residual palladium catalyst in Heck reactions may effectively mediate the addition of hydrogen to the newly substituted alkene [13][14][15]. Thus, following complete Heck cyclisation, as judged by TLC analysis, the

Oxidative cyclization of alkenols with Oxone using a miniflow reactor

• Yoichi M. A. Yamada,
• Kaoru Torii and
• Yasuhiro Uozumi

Beilstein J. Org. Chem. 2009, 5, No. 18, doi:10.3762/bjoc.5.18

• molecular diffusion path in narrow space reactors often drastically improve the efficiency of a given chemical reaction. As a case in point, we have previously developed a catalyst-installed microflow reactor where a membranous polymeric palladium catalyst was deposited inside a micro-channel reactor at the

Understanding the mechanism of Pd-catalyzed allylic substitution of the cyclic difluorinated carbonates

• Jun Xu,
• Xiao-Long Qiu and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2008, 4, No. 18, doi:10.3762/bjoc.4.18

• should be temporarily generated once the compounds 1 or 4 were treated with palladium catalyst. Thus, α-substitution products should be afforded considering the steric effects. However, only γ-substitution products 2–3 and 5 were isolated in our case, which, in our opinion, resulted from the specific

Synthesis of the Benzo- fused Indolizidine Alkaloid Mimics

• Daniel L. Comins and
• Kazuhiro Higuchi

Beilstein J. Org. Chem. 2007, 3, No. 42, doi:10.1186/1860-5397-3-42

• . [6][19] In this reaction, only the trans diastereomer was obtained as determined by analysis of the 1H-NMR spectrum of the crude product. This methodology is useful for the synthesis of various types of indolizidine alkaloids and their mimics. Treatment of 1a-i with 5 mol% of palladium catalyst, 2

• %, respectively (entry 1). The reaction in THF with 10 mol% of palladium catalyst at a lower reaction temperature gave 8k in 67% yield (entry 3). [22] Scheme 3 shows a method for substitution at the α-position of N-acyldihydropyridone 11. Our laboratories have reported C-5 substitution of 5-iodo-1,2